RESTORATIVE DENTAL MATERIALS

A COMPARATIVE EVALUATION OF SURFACE MICROHARDNESS OF THREE RESTORATIVE MATERIALS WHEN EXPOSED TO ACIDIC BEVERAGES

Abstract

Introduction: Erosion is an escalating problem in all age groups. Dental erosion
can be defined as painless irreversible loss of dental hard tissue due to chemical process
without the involvement of microorganisms. There are several causes of erosion including
acidic foods and drinks. They are not only harmful to teeth but it is one of the main causes of
failure of restoration. Erosion is one of the main challenges to restorative materials. Therefore,
the restorative materials used in the mouth should resist or show minimal change in these
situations. A variety of restorative materials are currently recommended for erosive lesions,
including resin modified glass ionomer cement, resin composite and amalgam. Each material
has its own advantages and disadvantages, which are considered before selecting them as
restorative materials. Objectives: To compare the surface micro-hardness of three restorative
materials when exposed to three acidic beverages and distilled water. Study design: This was
an experimental study. Setting: de’Montmorency College of dentistry in collaboration with
Pakistan council of scientific and industrial research (PCSIR) Lahore. Period: 6 months, Nov
2014- April 2015. Material & Methods: Ninety six disc specimens prepared with resin modified
glass ionomer, resin composite and amalgam restorative materials. The initial surface microhardness
test was carried out at 1 day after mixing (before immersion) using micro-hardness
testing machine. After base line study of micro-hardness the material specimens were subjected
to one of the storage media which was comprised of cola, apple juice, orange juice and distilled
water as control. Quantitative assessment of final surface micro-hardness was done at 2, 5 and
7 days after immersion. The values obtained as base line and final vickers hardness number
(VHN) for each specimen were subjected to statistical analysis. Results: Exposure to acidic
beverages decreased the surface micro-hardness of all the three restorative materials (P<0.05),
while distal water did not affect the surface micro-hardness of any material. The resin modified
GIC showed greatest reduction in surface micro-hardness as compared to Amalgam and Resin
Composite. The cola produced the greatest degradation effect. Conclusion: Selection of
restorative materials should be considered in patients with tooth surface loss, especially those
with high risk for erosive conditions. In terms of materials evaluated for this study Amalgam and
Resin Composite provides the greatest stability under acidic conditions.